The present invention relates to light-guide devices and, in particular, it concerns a light guide device which has a well-defined optical cutoff edge, and corresponding methods for producing such devices.
When manufacturing optical devices, it is often desirable to provide a light guiding device with a complex form in which different regions have surfaces angled with selected non-rectilinear orientations. Examples of such devices relevant to the present invention include, but are not limited to, light guiding elements with coupling-in configurations, and regions of transition between light guiding elements with different transverse dimensions and/or different orientations.
FIGS. 1A and 1B illustrate two examples of devices which include a light guiding element together with a coupling-in prism corresponding to FIGS. 3 and 7, respectively, of PCT Publication No. WO 2015/162611. Referring to the original reference numerals of those drawings in parentheses, each of these devices has a light guiding element (20) with first and second parallel faces (26), and a coupling prism (44, 54) for attachment to the light guiding element so as to provide a suitably angled input surface so that light can be introduced close to the normal to a surface (46, 58) of the prism and then enter the light guide at an angle desired for internal propagation of the light by internal reflection at surfaces (26).